Can we talk about fetal bovine serum in vaccines? - Page 2 - Mothering Forums
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#31 of 39 Old 11-22-2007, 03:13 PM
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Originally Posted by mamakay View Post
What about the 15-85% of vets and animal handlers who are seroconverted?
What about the kids with it (well, some pestivirus...) in their stools?
Seroconversion or antibody response isn't implicit for infection. Has virus been recovered from stool or just viral fragments?

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Suger water? Rotateq appears to beflavored with something babies like, so something that babies equally liked would work, it seems.
Oh, I see where you are coming from, palatability. But go back to our discussions about the Gardasil trials. The inactive ingredients are not being tested, only immunogenicity and safety of the experimental antigen is. It is the only way to control for the genuine effect of the vaccine. Now go eat your adolescent Meleagris serum.

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#32 of 39 Old 11-22-2007, 03:56 PM
 
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Seroconversion or antibody response isn't implicit for infection
I dunno...as a general rule, you don't seroconvert unless you were actually infected.
If it just barely took off but didn't make it, you won't get a humoral response. It's why you can't just drink IPV or the MMR and become immune.
You know?
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Has virus been recovered from stool or just viral fragments?
I'm not sure. How would that many viral fragments end up in kids' stools without infection?
Those were urban kids with bad enough gastro illness to be at the ER.

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Oh, I see where you are coming from, palatability. But go back to our discussions about the Gardasil trials. The inactive ingredients are not being tested, only immunogenicity and safety of the experimental antigen is.
I'm still not seeing *why* sugar water *wouldn't* work as a placebo.
Can you explain it to me like I'm a 2 year old?
Rotateq is clear, watery and sweet.
What would be wrong with a suger water placebo?
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#33 of 39 Old 11-23-2007, 01:17 AM
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Originally Posted by mamakay View Post
I dunno...as a general rule, you don't seroconvert unless you were actually infected.
If it just barely took off but didn't make it, you won't get a humoral response. It's why you can't just drink IPV or the MMR and become immune.
You know?
Sure you can. For instance we can mount a humoral immune response to food proteins or anything else that the immune system recognises as non-self. There is probably some dose-dependency, host factors and route of entry at work here too. I have finally ordered that 1989 Lancet article so I will let you know what that has to say if you don't have it.

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I'm not sure. How would that many viral fragments end up in kids' stools without infection?
Those were urban kids with bad enough gastro illness to be at the ER.
Could be coincidental because if the BVDV is replicating and causing clinical illness, intact virus should be able to be recovered


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I'm still not seeing *why* sugar water *wouldn't* work as a placebo.
Can you explain it to me like I'm a 2 year old?
Rotateq is clear, watery and sweet.
What would be wrong with a suger water placebo?
Like a 2 year-old huh? MK, did you do your poopies and put your jammies on? That's a good girl, now come here and Auntie SM will tell you a story. There is the double blind factor. The recipient and the administrator must not be able to detect a difference. Yes, infants in a trial would be less of a factor but not for the administrator.

You must limit variables in order to measure the immune response to the antigen itself as opposed to non-specific responses to other vaccine constituents.

This type of placebo controls for the placebo effect which, in this case would not be a factor for the recipient but so for the parent(s) and study investigators. There must be a quantitative effect greater than the placebo and a placebo consisting of something else completely different does not allow for an accurate measure of the experimental effect.

OK, here is an analogy; you wish to determine if a more expensive gasoline will improve your gas mileage. You normally drive on surface roads to work and blast your air conditioner. If you begin using the expensive gasoline, drive on highways and turn your air conditioner off, how will you determine if the expensive gasoline had an effect when you have not controlled the other variables that would also affect gas mileage?

SM
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#34 of 39 Old 11-23-2007, 08:38 AM
 
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Sure you can. For instance we can mount a humoral immune response to food proteins or anything else that the immune system recognises as non-self.
But that's generally something which doesn't happen. It can. But it's the exception rather than the rule.

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There is probably some dose-dependency, host factors and route of entry at work here too.
There's going to be a LOT of that. If the virus doesn't replicate, it has to be injected and you need millions, or 10's of millions, or hundreds of millions of virus particles to reliably get a humoral response.
Just out of curiosity, I looked to see what % of people have antibodies to feline leukemia virus, since it's not something that can infect people, but exposure should be fairly common:
http://www.nature.com/nature/journal.../273463a0.html

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I have finally ordered that 1989 Lancet article so I will let you know what that has to say if you don't have it.
Cool. I'm curious.

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Could be coincidental because if the BVDV is replicating and causing clinical illness, intact virus should be able to be recovered
I'm still thinking it would't have been recovered at all if it wasn't intact.

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There is the double blind factor. The recipient and the administrator must not be able to detect a difference. Yes, infants in a trial would be less of a factor but not for the administrator.
But it's clear, seems to have the thickness of water, and "appears" to taste like sugar water.

I'm still not seeing what would be wrong with a sugar water placebo for rotateq.
How would anyone know the difference?
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#35 of 39 Old 11-23-2007, 05:48 PM
 
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Originally Posted by Science Mom View Post
OK, here is an analogy; you wish to determine if a more expensive gasoline will improve your gas mileage. You normally drive on surface roads to work and blast your air conditioner. If you begin using the expensive gasoline, drive on highways and turn your air conditioner off, how will you determine if the expensive gasoline had an effect when you have not controlled the other variables that would also affect gas mileage?
SM
Oh, my god, SM, that is - no sarcasm at all here - seriously the best explanation I've yet heard as to why vaccines aren't tried against totally neutral placebo.

(placebae? )

Thank you, that actually clears up a big, big disconnect for me.
I'm not saying I've jumped ship or anything, I still have many, many more questions. But that analogy is lovely.
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#36 of 39 Old 11-23-2007, 06:16 PM
 
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That is an interesting explanation/parallel SM.

The problem is that you need to know that the placebo is not going to have any independent effects.

So, for example, the aluminum in the gardasil placebo would have been okay if they had first run tests giving people the placebo to see how they reacted. In other words, testing the non-inert placebo against an inert placebo. Then you would have a real base line for the actual study.

Ditto with the placebo for the rotavirus vax. If it had been tested against an inert placebo and the lack of reaction documented THEN it would be okay to use it as a placebo in a real trial.

I think someone is skipping a step or two.
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#37 of 39 Old 11-24-2007, 02:51 PM
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Originally Posted by mamakay View Post
But it's clear, seems to have the thickness of water, and "appears" to taste like sugar water.

I'm still not seeing what would be wrong with a sugar water placebo for rotateq.
How would anyone know the difference?
In such a case you could certainly mimic the physical properties but not the physiological properties. Does that make sense?

Deborah, You are still looking for independent safety trials for the vaccine constituents that are not novel formulations therefore don't need to be tested alongside vaccine efficacy/safety studies. They are separate entities.

ktbug, Thank-you for your kind words. That made my day and is much appreciated.

SM
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#38 of 39 Old 11-24-2007, 03:03 PM
 
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In such a case you could certainly mimic the physical properties but not the physiological properties. Does that make sense?
It's not supposed to even have physiological properties!
What properties would it have?
We're talking about a thimble full of what's supposed to be an inert substance!
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#39 of 39 Old 11-24-2007, 09:44 PM
 
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Originally Posted by mamakay View Post
It's not supposed to even have physiological properties!
What properties would it have?
We're talking about a thimble full of what's supposed to be an inert substance!
What they are assuming is an inert substance...

because it has been in use for many years...

like the aluminum in the gardasil placebo
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